Volume 70 • April 2011 57 Sugaring for stag beetles – different feeding strategies of Lucanus cervus and Dorcus paralellipipedus by Maria Fremlin (12447) 25 Ireton Rd, Colchester, Essex CO3 3AT, UK http://maria.fremlin.org and Paul Hendriks Hoofdstraat, 243 9828 PC Oostwold, The Netherlands [email protected] Introduction The stag beetle Lucanus cervus (L.) (Coleoptera: Lucanidae) will feed on sugary liquids either from sap runs or ripe juicy fruits; an old Kent name for stag beetles, cherry-eaters, attests to their strong liking for this fruit by males in particular (Krenn et al., 2002; Fremlin, 2004). They imbibe liquid with their feathery tongues, the two central setaceous parts between their mandibles. In some cases in the Netherlands, on sap runs up to 20 beetles have been seen licking sap, mating and males fighting (Gerrit Rekers, pers. comm. and seen by PH). In general the females stay for a few days, whereas males stay much longer. The large males often stand over the females, while smaller males try to get hold of the females and mate with them. The large males chase away the smaller ones, but sometimes a smaller male succeeds in mating with a female. Gerrit Rekers found several dead males in the vicinity of a sap run. In the UK, however, there are no records of stag beetles L. cervus gathering at sap runs although there are some from continental Europe (Chop, 1893; Tippmann, 1954; Mamonov, 1991; Tochtermann, 1992; Jansson, this issue). MF has observed in her urban area courtship behaviour very similar to that at sap runs, but in the vicinity of breeding sites, or freshly cut trees. These gatherings occur in the evening at the beginning of the season and are of very short duration. Males may also gather and fight for females in crevices; they will come back as long as the females stay there even though they cannot mate with them (Fremlin, 2003; 2009; unpublished). Natural gatherings of stag beetles such as may occur at sap runs enable direct information of their behaviour to be collated. We can determine their fidelity and comings and goings with some ease. In 2009 PH asked MF to set up an artificial sap run in her garden in order to observe them at close range throughout the flight season. We chose 58 Bulletin of the Amateur Entomologists' Society maple syrup as an attractant because stag beetles are fond of it. In captivity the males feed on it frequently and the females do so when they appear in between egg laying sessions. Furthermore, maple syrup is the only tree sap that is readily available. After two seasons of intensive field work we have only partial answers to our primary interest, but unexpectedly gathered interesting information about the lesser stag beetle Dorcus parallelipipedus (L.) Methods Two patches, each approximately 11x13 cm2, were cut from a terrycloth towel and were nailed to a couple of cherry stumps in Colchester, Essex at TL986244 in the garden of MF. The cherry trees were felled respectively in 2002 and 2005; the area has been an active breeding ground for some time for both L. cervus and D. parallelipipedus. One patch was placed on the top of the 2002 stump (height 70 cm, diameter 30 cm) and the other was placed half way up the trunk of the 2005 stump (height 76 cm, diameter 53 cm); they were left in situ until the following year. In 2010 a third patch was placed on Figure 1. Female D. parallelipipedus surrounded by black garden ants (L. niger). 07/08/2009, 2203 hrs. Volume 70 • April 2011 59 Figure 2. Male D. parallelipipedus under an old lady moth (Mormo maura L.) with black garden ants (L. niger) and another old lady moth in the background. This male appeared on four occasions. 05/08/2009 2203 hrs. a walnut tree at a height of 145 cm. This tree is 90 cm from the stumps. The general area of the stumps faces south. From mid May until early September the patches were refreshed daily at about 1900 hrs as follows. They were first sprayed with water with a spray gun and then maple syrup was applied with a drinking straw. The drinking straw was kept inside a small jar together with a small amount of syrup, covered with cling-film and refrigerated. A 330 g bottle of Sainsbury’s Pure Canadian Maple Syrup was sufficient for one season. The patches and surrounding street and alleyway were monitored daily from 2130 hrs; the overall area covered was roughly 40 m x 210 m. In 2010 this route was extended to include monitoring of a freshly cut stump in a nearby street, about 120 m away (Fremlin, 2010a). All times are quoted in British Summer Time (BST). Captured beetles were measured with a ruler, weighed with a Salter Pocket Electronic Diet Scale model 1250 with 0.1 g increments, marked and released. Their elytra were punctured with a needle following 60 Bulletin of the Amateur Entomologists' Society Mendéz (2008). In the first year these punctures were painted over with a Tippex pen, but this was replaced in 2010 by an Edding 750 marker, coloured white for the males and pink for the females. This extra marking speeded up the identification of recaptures in the dark, particularly D. parallelipipedus which are not as strongly dimorphic as L. cervus. Results Stag beetles shared the maple syrup patches with quantities of black garden ants Lasius niger (L.) and woodlice, both of the latter appearing as soon as the patches were recharged. Slugs came later on in the evening and in 2009 moths visited (Figures 1-3).2009 season Figure 3. Juvenile slug (Arion ater L.) crawling over a feeding male L. cervus, plus woodlouse (Oniscus asellus L.) and black garden ants (L. niger). 14/07/2010 2219 hrs. Nocturnal feeding L. cervus were generally unresponsive to sound or light, or even a slug (Figure 3). In contrast D. parallelipipedus were very sensitive to sound and in particular to light and thus had to be photographed and caught quickly. In both seasons in the monitored areas generally, there were far more sightings of L. cervus than of D.parallelipipedus but by the stumps or on the syrup patches the reverse was true (Table 1). Volume 70 • April 2011 61 Season 16 May – 9 September 2009 16 May – 5 September 2010 No. of markedbeetles Sightingsin the monitoredarea Sightingsby the stumps Sightingson the syrup patches No. of markedbeetles Sightingsin the monitoredarea Sightingsby the stumps Sightingson the syrup patches L. cervus Male 51 99 16 5 58 146 28 4 Female 33 68 9 0 53 107 28 2 Unknown 32 3 0 42 1 0 Total 84 199 28 5 111 295 57 6 D. parallelipipedus Male 17 55 42 34 13 69 45 31 Female 17 33 13 11 19 32 11 3 Total 34 88 55 45 32 101 56 34 Table 1 – Stag beetle sightings during 2009 and 2010, Colchester, Essex. Lucanus cervus L. cervus emerged on 19 May and between 10 and 23 June there were five feeding sightings of three males. One was observed three times on the horizontal patch, twice in the same day; all males had been captured first nearby. There were no sightings of feeding females. The longest time between recaptures was 37 days for a rather worn female in the general area of the stumps which travelled a distance of at least 95 m. A male was recaptured dead (trodden) after nine days having travelled a distance of at least 59 m. Dorcus parallelipipedus D. parallelipipedus was first sighted on 19 May and they fed actively from 29 May until 31 August. The majority were males of which 42 were in the general area of the stumps and 34 at the feeding patches where nine males came regularly, some many times and the most assiduous recaptured seven times. Some feeding males were first captured elsewhere, one travelling at least 70 m over 20 days, another 107 m over four days. There were significantly fewer sightings of feeding females, namely 11 representing four individuals. Two of these were also first captured 62 Bulletin of the Amateur Entomologists' Society elsewhere, one having travelled at least 79 m in 60 days, another 32 m in nine days. 2010 season Lucanus cervus In spite of a late first emergence on 3 June 2010, this was a good year for L. cervus and there was a doubling of sightings in the general area of the stumps. However, numbers of feeding sightings stayed about the same as those of 2009 and were late. Between 12 and 23 July four males were sighted once and one was spotted feeding in the morning. Another male was seen twice, close to the syrup patches. There were two sightings of feeding females, both rather worn; one on 25 July (Figure 4) and the other one at the end of the season on 16 August was found dead nearby four days later. Figure 4. Female L. cervus with rather worn front tibiae teeth. 25/07/2010, 2159 hrs. All individuals were first captured within 5 m of the general area of the stumps. The longest time between recaptures was by the freshly cut stump for beetles that had been first captured there; a dead male (trodden) Volume 70 • April 2011 63 after, 36 days and a very worn female after 19 days, she died the next day. Dorcus parallelipipedus D. parallelipipedus was first sighted in the area on 18 May and the feeding sightings were from 7 June until 30 August.